Help needed to model inertial effects to my vertical water pumping circuit

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immanuelkeba 2024-1-11

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https://ww2.mathworks.cn/matlabcentral/answers/2068766-help-needed-to-model-inertial-effects-to-my-vertical-water-pumping-circuit

评论： immanuelkeba 2024-1-30

Hi!!

I am simulating a pumping circuit that have three pumps whose outputs are combined together in a single pipe which is vertical in position. The inputs signals for these pumps are as follows

Due to this varied signal, there will be inertial effects in the water column that exerts pressure at the bottom of the vertical pipe, which I want to find out through simulink simulation. Could you help me do that? I tried with "Fluid Inertia" model. But that doesn't show any pressure spikes in the pressure plot? Pipe blocks available in simulink don't account for inertial effects. But surely there will be pressure spikes in the actual pumping. Could anyone help to model this phenomena in Matlab simulink? This is quite urgent for my research.

Following is the circuit

Pressure plot

Thing is how to get that pressure spikes? That's my only concern in this problem. Please help me out!!!

You may contact me on immanuel-proj.niot@gov.in

Thanks

Immanuel Keba

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immanuelkeba 2024-1-17

编辑：immanuelkeba 2024-1-17

Hi Yifeng Tang,

I went on to try something new. Instead of using a "Segmented Pipe LP" block which accounts for Fluid inertia, Resistive losses and Fluid compressibility, I tried using a "Hydraulic pipe LP" and "Fluid Inertia" blocks in series. The reason is I didn't get meaningful results by using a Segmented Pipe LP block (I got meaningless pressure undulations and flow rates at the outlet). I couldn't find any problom with my circuit for that.

Now the problem is, in which way should I connect them in series and what is the significance of it?

Hydraulic pipe LP at first followed by Fluid Inertia as shown

2. Fluid inertia block followed by Hydrauilc Pipe LP as shown

Flow happens from bottom to top up

Does the order make any significance?

Because I received meaningful pressure outputs but not the flow rates for configuration 1 and I received meaningful pressure as well as flow rate outputs for the configuration 2. I wish I get adviced and taught by you regarding the Order of the aforesaid connection.

Your response is highly appreciated.

Thanks

Immanuel Keba J

Yifeng Tang 2024-1-29

Usually the unphysical results are caused by unreasonable parameters or driving boundary conditions. But since you can't share the model here, I won't be able to tell. Given that, my suggestion is to complete your conversion to the Isothermal Liquid domain. As you go through the blocks, you may notice something to pay attention to.

To measure the actual pressure, connect the B port of the pressure sensor to a hydraulic reference. You'll then measure the pressure difference between Port A and the atomsphere, which will give you the gauge pressure. There are plenty of such examples in the Documentation. In more recent releases, the pressure sensor in the Isothermal Liquid domain contains an option to measure pressure difference (2 ports) or absolute pressure (1 port).

immanuelkeba 2024-1-30

Hi Yifeng,

Thank you so much for your guidance.

Grateful!!

Immanule Keba

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Physical Modeling Simscape Isothermal Liquid Models Upgrading Hydraulic Models to Use Isothermal Liquid Blocks

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